The iPhone minis were Apple's attempt to juice sales by providing a unique SKU catered to those us who like small phones (RIP my 12 mini). It was succeeded by the Plus model and if rumor has it, the Air. Single iPhone models have completely different goals than Vision Pro, which is a new platform that it bound to evolve in the next several years.
Quoted to revisit in a couple years
I won’t be surprised at all if they abandon ship on that project with some refocusing that’s needed.